[TowerTalk] Hermetic seals

[Steve Maki]

IME, in a typical zig zaggy trench with less than optimum corner bends 
and dirt that insists on getting into your glue, and a myriad of other 
defugalties that aren't anticipated while drawing it all out on paper, 
it's a miracle if the typical ham ends up with hermetically sealed 
joints in the ground, let alone the end terminations.

-Steve K8LX

On 2/27/2013 5:28 PM, Patrick Greenlee wrote:

> Jim, I don't disagree with your math but I do disagree with your
> statement that you can't seal the conduit.  Silicone rubber around snug
> fitting holes in a PVC pipe cap are sufficient but if you want to get
> super serious you can use compression type bulkhead feed through
> fittings, the kind with rubber corks with holes for the wire work very
> well.  There are others made with O rings that seal good enough to be
> used on oceanographic instruments intended to stay water tight at great
> depths. My 3 inch buried conduit is dry (I have a pull string and can
> swab the bore but have never found water.) The PVC pipe caps can be
> installed with an external bead of silicone caulk or Excel rather than
> PVC cement. This gives a good seal but can be easily cut with a utility
> knife to gain access and reassembled with more caulk.
>
> Patrick AF5ck